Ventral Tegmental Area (VTA) is the area that synthesizes dopamine, which then sends to nucleus accumbens. Nucelus accumbens is the pleasure center, and it is stimulated by the neurotransmitter dopamine from VTA. VTA also sends dopamine to prefrontal cortex which regulates and controls these impulses. The locus coeruleus is the area packed with norepinephrine; and when stimulated by a lack of the addictive substance, will drives the person to do anything necessary to obtain a fix.

Illustration of the structures that compose the limbic system in the brain, including the amygdala, hippocampus, hypothalamus, nucleus accumbens, basal ganglia, and ventral tegmental area and substantia nigra.

Dopamine Pathways. In the brain, dopamine plays an important role in the regulation of reward and movement. As part of the reward pathway, dopamine is manufactured in nerve cell bodies located within the ventral tegmental area (VTA) and is released in the nucleus accumbens and the prefrontal cortex. Its motor functions are linked to a separate pathway, with cell bodies in the substantia nigra that manufacture and release dopamine into the striatum (Image Source: WIkipedia)

Rodents that had been exposed to stress had a weakened alcohol-induced dopamine response and voluntarily drank more alcohol compared to controls, a new study has found. The blunted dopamine signaling to ethanol arose due to changes in the circuitry in the ventral tegmental area, the heart of the brain's reward system.

Gut Brain Connection. Approx 90% of the human body's total serotonin is located in the gut, where it is used to regulate intestinal movements. The remainder is synthesized in serotonergic neurons of the CNS, where it has various functions. These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive functions, including memory and learning. Modulation of serotonin at synapses is thought to be a major action of several classes of pharmacological…